It might have been better to mention all that in the first place, the more info you can give about an issue the better.
What, typically, is in these 20 tabs that you have open?
(A forum, a shopping site like Amazon, You tube videos, TV/film streaming, etc.?).
There's couple of tests you can do to try and narrow down what the problem may be.
Suspend Inactive Tabs is a fairly new setting so let's look at that first:
(I do have a suspicion of what <em>might</em> be happening if you put a laptop to sleep with that setting on).
As you say you currently have 'suspend inactive tabs' set to ON then try setting it to OFF, visit each tab in turn then close the lid and wait a while, reopen the lid and see if that has changed the time it takes those tabs to refresh/reload.
That will tell you/us if it's that setting causing an issue with waking from sleep.
If nothing has changed then:
What happens if you only have one or two tabs open (say to something simple like the google homepage) when you close then reopen the lid?
Is it still as slow to reload that single tab?
(Does it change if you have 'suspend inactive tabs' on or off?)
If it's only affecting CCleaner browser, and only recently, then you have to suspect that it's a change to the browser causing it.
Although it doesn't help that Win 10 updates at least every month so you always have to bear that in mind as well.
For instance I've noticed a slowdown in the loading times of various apps since I updated to Win10 2004, but not to the extent that you report.
After that Windows update my Firefox in particular did get very slow to load, around 40 secs, but a Firefox refresh sorted that out and it's back down to about 5 or 6 secs.
We haven't seen any other reports of tabs in CCleaner Browser suddenly becoming slow to load. (yet?).
It may be that there is an issue with closing the laptop to put it to sleep when you have multiple tabs open, but without further reports/testing it's hard to tell.
Obviously if it's a widespread problem then it needs to be looked at by the browser developers.
On the other hand if it isn't widespread then it's more likely to be a setting (or an application conflict) on a particular users machine and modifying/updating the browser would be unlikely to fix that.